Gaya, also rendered Kaya or Kara, is the presumed language of the Gaya confederacy in southern Korea. It is supposedly attested from thirteen toponyms, but it cannot be certain that these reflect the Gaya language itself rather than an earlier language.[1] Only one word survives that is directly identified as being from the language of the Gaya confederacy.

It is not clear if this "pre-Kara" was related to the language of the later Gaya confederacy, of which only four words survive.[2] In volume 34 of the Samguk sagi, a note for the word 旃檀梁 states that, "In the Kaya language, 'gate' is called 梁." The Chinese character ⟨梁⟩ was used to write the Silla word for 'ridge', which was ancestral to Middle Korean 돌 *twol 'ridge', suggesting that the Gaya word for 'gate' may have been pronounced something like twol. This looks similar to Old Japanese*two/tö (門/戸) (modern Japanese to, 戸), meaning 'door, gate'.[2][3][4]

The apparently Japonic identity of the Kara toponyms constitutes part of the evidence for the Japanese–Koguryoic hypothesis. However, the Koguryo (Goguryeo) languages themselves came from further north; they may have been ancestral to Korean and replaced Japonic languages in southern Korea. As Gaya grew out of one of the Samhan nations, it may be that the Goguryeo-derived languages of Silla and of the Baekje elite were related to Korean, while the indigenous Samhan language of Baekje was related to (pre-)Gaya and Japanese.

The name Gaya is Korean, from the modern transcription 加耶 (伽倻). However, it was difficult to render the phonological shape of words in the languages of Korea by the use of Chinese characters, since hangul had not yet been invented, and thus a variety of historical forms are attested. (See Gaya confederacy.) Generally Gaya was transcribed as Kaya (加耶) or Karak (伽落), but the transcription in the oldest sources is Kara (加羅), and philological reconstruction points towards MC *kayia, from Ancient Chinese *kala = *kara.[1]Beckwith considers the pronunciation [kaɾa] "certain",[5] so the language is also known as Kara, for example in Ethnologue.